Introduction
The human heart is a critical organ in the nervous system, and it is responsible for sustaining life throughout its lifespan. The muscular organ is characterized by four major functionally distinct chambers and several valves responsible for regulating the normal flow of blood within the body (Litviňuková et al., 2020). It is found at the center of the chest between the lungs, underneath the thoracic cavity.
The Function of the Heart
The primary function of the human heart is to ensure that blood constantly flows by pumping it throughout the body (Willie et al., 2015). It is also responsible for delivering and replenishing oxygen, hormones, glucose, nutrients, and other components to the cells and tissues in various parts of the body (Miranda, 2019; Willie et al., 2015). Maintaining a constant blood flow also helps in ensuring adequate blood pressure in the body. It also removes carbon dioxide and waste from the body system.
Types of Blood Circulation
There are three major types of blood circulation. Pulmonary circulation involves the transfer of deoxygenated blood from the heart to the lungs and then the movement of oxygenated blood from the lungs back to the heart (Visible Body, 2020).
Systematic circulation is distinct from pulmonary circulation in the sense that oxygenated blood is carried from the heart to all other organs and tissues in the body, and deoxygenated blood is transferred back to the heart (Visible Body, 2020).
Coronary circulation is responsible for replenishing the heart with oxygen and involves the supply of oxygenated blood to the heart. Other organs, such as the brain, depend hugely on the steady supply of fresh, oxygenated blood to survive (Miranda, 2019).
The External Structure of the Heart
The pericardium and walls of the heart make up the external structure. The pericardium is the membrane covering the heart, which comprises two layers: serous and fibrous (Saikat, 2016). It has three distinct layers (myocardium, endocardium, and epicardium) and a cavity, as illustrated above. It is responsible for preventing excessive stretching, insufflation, or inflation of the heart and protecting it by secreting a lubricant that reduces the risk of friction with adjacent organs (Saikat, 2016; Miranda, 2019). Moreover, the pericardium is responsible for holding this organ in its position (Saikat, 2016).
The Internal Structure of the Heart
The internal structure of the heart is more complex and consists of four chambers (which differ in terms of their morphology and function) and several blood vessels and valves which are responsible for controlling the flow of blood in the body (Litviňuková et al., 2020).
The four chambers (the left atrium, right atrium, left ventricle, and right ventricle) receive blood and pump it away from the heart.
The heart has three major blood vessels (veins, capillaries, and arteries) which distribute blood throughout the body.
Finally, the heart has two types of valves (atrioventricular valves and semilunar valves) which ensure that the blood flows in a single direction (Miranda, 2019).
References
Litviňuková, Talavera-López, C., Maatz, H., Reichart, D., Worth, C., Lindberg, E., Kanda, M., Polanski,K., Heinig, M., Lee, M., Nadelmann, E., Roberts, K., Tuck, L., Fasouli, E., DeLaughter, D., McDonough, B., Wakimoto, H., Gorham, J., Samari, S., … Teichmann, S. A. (2020). Cells of the adult human heart. Nature. Web.
Miranda, M., G. (2019). Structure and function of the heart. New Medical. Web.
Saikat, R. (2016).What is the structure of the pericardium? What is its function? Socratic. Web.
Visible Body (2020). Pulmonary Circulation and systemic circulation: the routes and function of blood flow. Web.
Willie, C. K., Tzeng, Y. C., Fisher, J. A., & Ainslie, P. N. (2014). Integrative regulation of human brain blood flow. The Journal of Physiology, 592(5), 841–859.